Extrusion apparatus



Patented Sept. 14, 1954 EXTRUSION APPARATUS Harold Corbett, East Orange,N. J., assignor to Halon Plastics, Inc., a corporation of New JerseyApplication March 14, 1951, Serial No. 215,545

2 Claims. 1

This invention relates to a molding structure and method for use eitheras an attachment or built in part of an extruder particularly forthermoplastic materials of any standard or other type, and whichprovides means acting as a pump to boost the pressure on the material.

It is especially aimed to provide a novel construction and method whichwill insure travel of the plastic material throughout the line ofadvance without any portion thereof becoming pocketed, static orstagnant, in order to avoid overworking or burning of the material.

A prime aim is to provide means wherein the objects mentioned areattained especially at the lateral extremities of the distributingbarrel.

Further in attaining the ends mentioned, an object is to provide adistributing screw conveyor means which acts as a pump to boost thepressure on the material and the axis of which conveyor crosses the lineof advance of the thermoplastic material, which conveyor has mainflights whose pitches are in opposite directions to spread thethermoplastic material laterally or away from such line, which conveyoralso has terminal flights of opposite pitch to the respective adjacentmain flights to return the thermoplastic material from the ends of thedistributing chamber toward said line, thence through a slot or slotsand through the pass of finishing rolls to emerge in sheet or otherform.

Various additional objects and advantages will become apparent from aconsideration of the description following taken in connection with theaccompanying drawings illustrating an operative embodiment, and wherein:

Fig. 1 is a longitudinal sectional view through the improvements inconnection with a fragment of a conventional extruder, such sectionbeing taken approximately on the plane of line l-l of Fig. 2;

Fig. 2 is an end elevation of my improvements looking from the right ofFig. 1 in accordance with line 2 and the arrow in the latter figure; and

Fig. 3 is a horizontal sectional view taken on the plane of line 33 ofFig.2.

Referring specifically to the drawings, wherein like referencecharacters designate like or similar parts throughout the differentviews, an eX- truder is fragmentarily shown of which I is the dischargeend of the barrel and II is the conveying screw suitably rotatablyoperated in the bore or chamber 12 of such barrel. This representationof an extruder is to be taken as conyentional inasmuch as myimprovements are applicable to any standard or other extruder, forinstance that disclosed in my co-pending application for Method andMachine for Combined Extruding and Injection Molding, Serial No,156,207, filed April 15, 1950. It is clear that the usually heatedthermoplastic material is supplied in fluid condition through thechamber H by the screw 1 I alone or augmented by pressure as preferred,and discharged through the right hand end of the barrel ID withreference to Fig. 1.

In carrying out my invention, I provide a head or unit generallydesignated it. This unit consists of a base or attaching plate M, and itmay be permanently or detachably secured to the barrel I E1 or even forman integral part thereof. As shown, plate 14 is detachably secured tosaid barrel In as by means of bolts 15. All other parts of myimprovements are connected to or mounted from said plate M preferablydetachably to facilitate inspection, assembly and repair. Like thebarrel IE3, in order to properly maintain the condition and plasticizethe material, such plate is suitably heated. This may be effected in anysuitable manner with steam, hot water, oil or the like, but as shown,conveniently the plate has fitted therein any number of conventionalelectric heating units I6. In registry or alignment with the bore l 2,said plate M has a discharge opening or throat H to receive the plasticmaterial, and it will be noted that such opening is preferablyconstricted toward the forward end and at such end the constrictionwidens or flares horizontally as shown in Fig. 3 at 18.

Secured as by means of bolts [9 against the forward face of the plate 14is a horizontal elongated distributing barrel 2!) which is hollow fromend to end to provide a distributing chamber 2|. The rear wall of barrel2!) has a slot 22 registering with the opening ll at the flare E8 inorder to receive the plastic material. A horizontal screw-member 23rotates clockwise within the distributing chamber 2| to discharge thematerial through a relatively narrow elongated slot or nozzle opening inthe front wall of the distributing barrel at preferably the same levelas the axis of the distributing screw 23. While a single slot 24 hasbeen shown, it is to be understood that this single slot may be replacedby any plurality of slots or openings desired, and also that the shapeand proportions may be varied at will.

It is to be emphasized that the screw 23 and associated parts act as apump and boost the pressure on the material.

At each side of the head It is a plate 25 detachably fastened thereto asby means of bolts '26. Said plates 25 extend forwardly beyond the platethrough the slot 24 or the equivalent.

3 l4, particularly covering and closing the ends of the distributingchamber 2|.

Reverting to the distributing screw 23, it comprises a shaft 2'! whichis journalled in both side plates 25. On said shaft 21 are two mainflights or threads 28 which may be connected to each other approximatelyin line with the longitudinal axis of the feed screw II, and which twoflights are of opposite pitch and extend in opposite directions in orderthat the material received in I the distributing chamber 2| will bespread or distributed laterally from the center of that chamber towardthe opposite ends thereof. Adjacent the opposite ends of thedistributing chamber 2|, shaft 27 is provided with auxiliary threads orflights 28, which it will be noted are in scraping contact with the endwalls for said distributing chamber 2| afforded by said end plates 25.These flights 29 are of opposite pitch or extend in opposite directionsand in directions respectively reversed to the adjacent main flights 28so that material in the distributing chamber adiacent the ends of thelatter will not become pocketed, static or stagnant, but will bereturned toward the junction of the flights 23 and by them fed throughthe opening 24.

In front of said opening 24, the discharged body or sheet of plasticmaterial as suggested in dotted lines at 30 in Fig. 1, is contacted andfed forward by upper and lower horizontal rolls 30 carried by shafts 3|suitably journalled in the side plates 25. The action of the rolls 30and the pass or space between them maintains the correct finish andthickness of the material, such material after passage between the rolls3!! being in form, shape and condition for commercial or other use.

Rolls 30 are driven in any suitable manner in opposite directions assuggested by the arrows in Fig. 1. For instance one of the shafts 3| isdriven from the drive mechanism for the screw II, or from a separatesource of power. Such shafts 3| have intermeshing gears 32. From thelower shaft 3|, a conventional chain and sprocket drive 33 may beprovided for the distributing screw 23, although screw 27 may have aseparate or any other drive to vary the output and pressure.

In connection with the maintenance of the proper working temperaturesand conditions for the plastic material, rolls 30 are preferably hollowfor the circulation of water or oil therethrough in any conventionalmanner to cool the same.

In operation the heated and conditioned plastic material will besupplied from a chamber |2 by screw l I through the opening or throat I?and slot 22 into the distributing chamber 2| of barrel 23. In suchchamber the plastic material will be spread in opposite directions fromthe line of feed by the main flights 28 and passed Such material uponapproaching the ends or lateral extremities of the chamber 2| will beengaged by the flights 29 and returned thereby due to their oppositepitch or direction and their respective opposite pitch or directionrelative to the adjacent flights 28 during the line of feed and moved ordistributed forward thereby through the opening 24. Any of the materialwhich may engage the walls of the distributing chamber 2| will bescraped therefrom by the flights 29 after emerging through the slot 24,the material will enter the pass between rolls 30, contacted by thelatter, and to maintain the correct finish and thickness of the sheet orequivalent suggested at 30. It will thus be seen that the screw 23 actsas a pump and boosts the pressure of the material so that structureinsures travel of the plastic material throughout the line of feedwithout any portion thereof becoming pocketed, static or stagnant, andespecially at the ends of the distributing chamber 2|, which resultcannot be attained under existing conditions, due to fluctuation intemperature, slow-down in operation, and the like.

Various changes may be resorted to provided they fall within the spiritand scope of the invention.

I claim as my invention:

1. Apparatus of the class described comprising a member having a funnelshaped passage therethrough, walls forming an elongated cylindricalchamber communicating at its center with the small end of said passageand having its long axis perpendicular to the axis of the passage, saidchamber having an elongated narrow discharge slot disposed in the wallopposite said passage, a rod journalled for rotation in said chamber, afirst pair of screw flights of opposed pitch disposed on said rod andmeeting at the center of said chamber for forcing plastic material fromthe center toward the ends of said chamber and through said dischargeslot, and a short screw flight disposed at each end of said rod pitchedto force plastic material inwardly of said chamber.

2. The apparatus defined in claim 1 wherein a pair of spaced hollow feedrolls disposed on parallel axes is mounted adjacent said slot inposition to receive between them plastic material leaving said slot, andmeans for rotating said rod and said rolls.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 790,918 Du Pont May 30, 1905 1,302,484 Stratton et al. Apr.29, 1919 1,327,721 Mattison, Jr. Jan. 13, 1920 2,458,068 Fuller Jan. 4,1949 2,535,865 Poncelet Dec. 26, 1950 2,543,307 Swallow et al. Feb. 27,1951

